Footwear With A Sole Structure Incorporating A Lobed Fluid-Filled Chamber

ABSTRACT

A fluid-filled chamber for an article of footwear and a method for manufacturing the chamber are disclosed. The chamber may be incorporated into a sole structure of the footwear and includes a central area and a plurality of lobes extending outward from the central area. The lobes are in fluid communication with the central area and are formed from a first surface, a second surface, and a sidewall. The sidewall joins with the first surface with the second surface to seal the fluid within the chamber, but no internal connections are generally utilized to join interior portions of the first surface with interior portions of the second surface. The fluid within the chamber may be air at a pressure that is approximately equal to an ambient pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. patent application is a continuation of and claims priority toU.S. patent application Ser. No. 11/618,035, which was filed in the U.S.Patent and Trademark Office on 29 Dec. 2006 and entitled Footwear With ASole Structure Incorporating A Lobed Fluid-Filled Chamber, such priorU.S. patent application being entirely incorporated herein by reference.U.S. patent application Ser. No. 11/618,035 is, in turn, acontinuation-in-part application of and claims priority to U.S. patentapplication Ser. No. 11/508,113, which was filed in the U.S. Patent andTrademark Office on Aug. 22, 2006 and entitled Footwear With A SoleStructure Incorporating A Lobed Fluid-Filled Chamber, such prior U.S.patent application being entirely incorporated herein by reference. U.S.patent application Ser. No. 11/508,113 is, in turn, acontinuation-in-part application of and claims priority to U.S. Pat. No.7,128,796 issued Oct. 31, 2006, which was filed in the U.S. Patent andTrademark Office as U.S. patent application Ser. No. 10/620,843 on Jul.16, 2003 and entitled Footwear With A Sole Structure Incorporating ALobed Fluid-Filled Chamber, such prior U.S. patent application beingentirely incorporated herein by reference.

BACKGROUND

A conventional article of footwear includes two primary elements, anupper and a sole structure. With respect to athletic footwear, forexample, the upper generally includes multiple material layers, such astextiles, foam, and leather, that are stitched or adhesively bondedtogether to form a void on the interior of the footwear for securely andcomfortably receiving a foot. The sole structure has a layeredconfiguration that includes an insole, a midsole, and an outsole. Theinsole is a thin cushioning member positioned within the void andadjacent the foot to enhance footwear comfort. The midsole forms amiddle layer of the sole structure and is often formed of a foammaterial, such as polyurethane or ethylvinylacetate. The outsole issecured to a lower surface of the midsole and provides a durable,wear-resistant surface for engaging the ground.

Midsoles formed of conventional foam materials compress resilientlyunder an applied load, thereby attenuating forces and absorbing energyassociated with walking or running, for example. The resilientcompression of the foam materials is due, in part, to the inclusion ofcells within the foam structure that define an inner volumesubstantially displaced by gas. That is, the foam materials include aplurality of pockets that enclose air. After repeated compressions,however, the cell structures may begin to permanently collapse, whichresults in decreased compressibility of the foam. Accordingly, theoverall ability of the midsole to attenuate forces and absorb energydeteriorates over the life of the midsole.

One manner of minimizing the effects of the cell structure collapse inconventional foam materials involves the use of a structure having theconfiguration of a fluid-filled chamber, as disclosed in U.S. Pat. No.4,183,156 to Rudy, hereby incorporated by reference. The fluid-filledchamber has the structure of a bladder that includes an outer enclosingmember formed of an elastomeric material that defines a plurality oftubular members extending longitudinally throughout the length of anarticle of footwear. The tubular members are in fluid communication witheach other and jointly extend across the width of the footwear. U.S.Pat. No. 4,219,945 to Rudy, also incorporated by reference, discloses asimilar fluid-filled chamber encapsulated in a foam material, whereinthe combination of the fluid-filled chamber and the encapsulating foammaterial functions as a midsole.

U.S. Pat. No. 4,817,304 to Parker, et al., hereby incorporated byreference, discloses a foam-encapsulated, fluid-filled chamber in whichapertures are formed in the foam and along side portions of the chamber.When the midsole is compressed, the chamber expands into the apertures.Accordingly, the apertures provide decreased stiffness duringcompression of the midsole, while reducing the overall weight of thefootwear. Further, by appropriately locating the apertures in the foammaterial, the overall impact response characteristics may be adjusted inspecific areas of the footwear.

The fluid-filled chambers described above may be manufactured by atwo-film technique, wherein two separate layers of elastomeric film areformed to have the overall shape of the chamber. The layers are thenwelded together along their respective peripheries to form an uppersurface, a lower surface, and sidewalls of the chamber, and the layersare welded together at predetermined interior locations to impart adesired configuration to the chamber. That is, interior portions of thelayers are connected to form chambers of a predetermined shape and sizeat desired locations. The chambers are subsequently pressurized aboveambient pressure by inserting a nozzle or needle, which is connected toa fluid pressure source, into a fill inlet formed in the chamber. Afterthe chambers are pressurized, the nozzle is removed and the fill inletis sealed, by welding for example.

Another manufacturing technique for manufacturing fluid-filled chambersof the type described above is through a blow molding process, wherein aliquefied elastomeric material is placed in a mold having the desiredoverall shape and configuration of the chamber. The mold has an openingat one location through which pressurized air is provided. Thepressurized air forces the liquefied elastomeric material against theinner surfaces of the mold and causes the material to harden in themold, thereby forming the chamber to have the desired configuration.

Another type of chamber utilized in footwear midsoles is disclosed inU.S. Pat. Nos. 4,906,502 and 5,083,361, both to Rudy, and both herebyincorporated by reference. The chambers comprise a hermetically sealedouter barrier layer that is securely bonded over a double-walled fabriccore. The double-walled fabric core has upper and lower outer fabriclayers normally spaced apart from each another at a predetermineddistance, and may be manufactured through a double needle bar Raschelknitting process. Connecting yarns, potentially in the form ofmulti-filament yarns with many individual fibers, extend internallybetween the facing surfaces of the fabric layers and are anchored to thefabric layers. The individual filaments of the connecting yarns formtensile restraining members that limit outward movement of the barrierlayers to a desired distance.

U.S. Pat. Nos. 5,993,585 and 6,119,371, both issued to Goodwin et al.,and both hereby incorporated by reference, also disclose chambersincorporating a double-walled fabric core, but without a peripheral seamlocated midway between the upper and lower surfaces of the chamber.Instead, the seam is located adjacent to the upper surface of thechamber. Advantages in this design include removal of the seam from thearea of maximum sidewall flexing and increased visibility of theinterior of the chamber, including the connecting yarns. The processused to manufacture a chamber of this type, involves the formation of ashell, which includes a lower surface and a sidewall, with a mold. Thedouble-walled fabric core is placed on top of a covering layer, and theshell is placed over the covering layer and core. The assembled shell,covering layer, and core are then moved to a lamination station whereradio frequency energy bonds opposite sides of the core to the shell andcovering layer, and bonds a periphery of the shell to the coveringlayer. The chamber is then pressurized by inserting a fluid so as toplace the connecting yarns in tension.

A process for thermoforming a chamber is disclosed in U.S. Pat. No.5,976,451 to Skaja et al., hereby incorporated by reference, wherein apair of flexible thermoplastic resin layers are heated and placedagainst a pair of molds, with a vacuum drawing the layers into the mold.The layers are then pressed together to form the chamber.

The material forming outer layers of the chambers discussed above may beformed of a polymer material, such as a thermoplastic elastomer, that issubstantially impermeable to the fluid within the chamber. Morespecifically, one suitable material is a film formed of alternatinglayers of thermoplastic polyurethane and ethylene-vinyl alcoholcopolymer, as disclosed in U.S. Pat. Nos. 5,713,141 and 5,952,065 toMitchell et al, hereby incorporated by reference. A variation upon thismaterial wherein the center layer is formed of ethylene-vinyl alcoholcopolymer; the two layers adjacent to the center layer are formed ofthermoplastic polyurethane; and the outer layers are formed of a regrindmaterial of thermoplastic polyurethane and ethylene-vinyl alcoholcopolymer may also be utilized. Another suitable material is a flexiblemicrolayer membrane that includes alternating layers of a gas barriermaterial and an elastomeric material, as disclosed in U.S. Pat. Nos.6,082,025 and 6,127,026 to Bonk et al., both hereby incorporated byreference. Other suitable thermoplastic elastomer materials or filmsinclude polyurethane, polyester, polyester polyurethane, polyetherpolyurethane, such as cast or extruded ester-based polyurethane film.Additional suitable materials are disclosed in the '156 and '945 patentsto Rudy, which were discussed above. In addition, numerous thermoplasticurethanes may be utilized, such as PELLETHANE, a product of the DowChemical Company; ELASTOLLAN, a product of the BASF Corporation; andESTANE, a product of the B.F. Goodrich Company, all of which are eitherester or ether based. Still other thermoplastic urethanes based onpolyesters, polyethers, polycaprolactone, and polycarbonate macrogelsmay be employed, and various nitrogen blocking materials may also beutilized. Further suitable materials include thermoplastic filmscontaining a crystalline material, as disclosed in U.S. Pat. Nos.4,936,029 and 5,042,176 to Rudy, hereby incorporated by reference, andpolyurethane including a polyester polyol, as disclosed in U.S. Pat.Nos. 6,013,340; 6,203,868; and 6,321,465 to Bonk et al., also herebyincorporated by reference.

The fluid contained within the chamber may include any of the gassesdisclosed in U.S. Pat. No. 4,340,626 to Rudy, such as hexafluoroethaneand sulfur hexafluoride, for example. In addition, some chambers enclosepressurized nitrogen gas or air.

SUMMARY

A chamber for an article of footwear may include a first surface, anopposite second surface, and a sidewall extending between edges of thefirst surface and the second surface. The sidewall is joined with thefirst surface and the second surface such that no internal connectionssecure interior portions of the first surface to interior portions ofthe second surface. A fluid is sealed within the chamber at a pressurebetween an ambient pressure and five pounds per square inch of theambient pressure. Furthermore, a plurality of lobes extend outward froma central area of the chamber. The lobes are defined by the firstsurface, second surface, and sidewall, and the lobes are in fluidcommunication with the central area.

The first surface and the second surface may have a planarconfiguration. Alternately, one of the surfaces may be curved. Inaddition, portions of the sidewall positioned between the lobes may havea sloped configuration, and the portions of the sidewall adjacent distalends of the lobes may have a substantially vertical slope.

The lobes may be configured to extend radially outward from the centralarea. Accordingly, the lobes may extend outward in different directionsfrom the periphery of the central area. The number of lobes may varysignificantly within the scope of the invention. The lobes define spaceslocated between adjacent lobes. When incorporated into an article offootwear, the chamber will be at least partially encapsulated within apolymer foam material. Accordingly, the polymer foam will extend betweenthe lobes to form columns. In general, the surface of the columns willcontact the sidewall and have the shape of the spaces between theadjacent lobes. Accordingly, the columns will have a slopedconfiguration that corresponds with the sidewall slope.

The material that forms the chamber will generally be a polymer, such asa thermoplastic elastomer, thereby providing the structure of a bladder.Alternately, the chamber may be formed as a void within a midsole of thefootwear. Although a plurality of fluids may be utilized within thechamber, air generally provides properties that are suitable for theinvention.

Another aspect relates to a method of manufacturing a fluid-filledchamber for an article of footwear. The method involves positioning aparison between a first portion and a corresponding second portion of amold. The parison is then bent with contours of the mold as the firstportion and the second portion translate toward each other, the contoursof the mold being positioned separate from a cavity within the mold, thecavity having a shape of the chamber. Opposite sides of the parison arethen shaped to form the chamber within the cavity, and the oppositesides of the parison are bonded together.

The advantages and features of novelty characterizing the presentinvention are pointed out with particularity in the appended claims. Togain an improved understanding of the advantages and features ofnovelty, however, reference may be made to the following descriptivematter and accompanying drawings that describe and illustrate variousembodiments and concepts related to the invention.

DESCRIPTION OF THE DRAWINGS

The foregoing Summary, as well as the following Detailed Description,will be better understood when read in conjunction with the accompanyingdrawings.

FIG. 1 is a side elevational view of an article of footwear having amidsole that incorporates a first chamber in accordance with the presentinvention.

FIG. 2 is a perspective view of the midsole depicted in FIG. 1.

FIG. 3 is a exploded perspective view of the midsole depicted in FIG. 1.

FIG. 4 is a perspective view of the first chamber.

FIG. 5 is another perspective view of the first chamber.

FIG. 6A is a top plan view of the first chamber.

FIG. 6B is a cross-section of the first chamber, as defined by sectionline 6B-6B in FIG. 6A.

FIG. 6C is another cross-section of the first chamber, as defined bysection line 6C-6C in FIG. 6A.

FIG. 6D is yet another cross-section of the first chamber, as defined bysection line 6D-6D in FIG. 6A.

FIG. 7 is a bottom plan view of the first chamber.

FIG. 8 is a side elevational view of another article of footwear havinga midsole that incorporates a second chamber in accordance with thepresent invention.

FIG. 9 is a perspective view of the midsole depicted in FIG. 8.

FIG. 10 is an exploded perspective view of the midsole depicted in FIG.8.

FIG. 11 is a perspective view of the second chamber.

FIG. 12 is another perspective view of the second chamber.

FIG. 13A is a top plan view of the second chamber.

FIG. 13B is a cross-section of the second chamber, as defined by sectionline 13B-13B in FIG. 13A.

FIG. 13C is another cross-section of the second chamber, as defined bysection line 13C-13C in FIG. 13A.

FIG. 13D is yet another cross-section of the second chamber, as definedby section line 13D-13D in FIG. 13A.

FIG. 14 is a bottom plan view of the second chamber.

FIG. 15 is an elevational view of the second chamber.

FIG. 16 is a perspective view of a mold for forming the second chamber.

FIG. 17 is a plan view of a first portion of the mold.

FIG. 18 is a plan view of a second portion of the mold.

FIG. 19 is a side elevational view of a parison positioned between thefirst and second portions of the mold prior to molding.

FIG. 20 is a side elevational view of the parison positioned between thefirst and second portions of the mold during an intermediate portion ofmolding.

FIG. 21 is a side elevational view of the parison positioned between thefirst and second portions of the mold during another intermediateportion of molding.

FIG. 22 is a side elevational view of a parison positioned between thefirst and second portions of the mold following molding.

FIG. 23 is a first perspective view of the second chamber formed in theparison.

FIG. 24 is a second perspective view of the second chamber formed in theparison.

FIG. 25 is a perspective view of the second chamber that highlights aposition of a parting line.

FIGS. 26 and 27 are side elevational views of another configuration ofthe footwear depicted in FIG. 8, wherein the midsole incorporates athird chamber in accordance with the present invention.

FIG. 28 is a perspective view of the third chamber.

FIG. 29 is another perspective view of the third chamber.

FIG. 30 is a top plan view of the third chamber.

FIG. 31 is a bottom plan view of the third chamber.

FIGS. 32 and 33 are elevational views of the third chamber.

FIG. 34 is a top plan view of another configuration of the thirdchamber.

FIG. 35 is a lateral side elevational view of yet another article offootwear having a sole structure that incorporates a fourth chamber inaccordance with the present invention.

FIG. 36 is a medial side elevational view of the article of footweardepicted in FIG. 35.

FIG. 37 is a perspective view of the sole structure.

FIG. 38 is a top plan view of the sole structure.

FIGS. 39A-39C are cross-sectional views of the sole structure, asdefined by section lines 39A-39C in FIG. 38.

FIG. 40 is an exploded lateral side elevational view of the solestructure.

FIG. 41 is a perspective view of the fourth chamber.

FIG. 42 is another perspective view of the fourth chamber.

FIG. 43 is a top plan view of the fourth chamber.

FIGS. 44A-44C are cross-sectional views of the fourth chamber, asdefined by section lines 44A-44C in FIG. 42.

FIG. 45 is a bottom plan view of the fourth chamber.

FIG. 46 depicts top plan views of three configurations of the fourthchamber.

FIG. 47 is a perspective view of the fourth chamber that highlights aposition of a parting line.

FIG. 48 is a top plan view of a portion of the sole structure anddepicting an alternate configuration.

FIGS. 49A-49C are cross-sectional views corresponding with FIG. 39A anddepicting alternate configurations of the sole structure.

FIGS. 50A and 50B are cross-sectional views corresponding with FIG. 39Band depicting alternate configurations of the sole structure.

FIGS. 51A-51D are top plan views corresponding with FIG. 43 anddepicting alternate configurations of the chamber.

DETAILED DESCRIPTION

The following discussion and accompanying figures disclose articles ofathletic footwear incorporating fluid-filled chambers in accordance withthe present invention. Concepts related to the footwear, and moreparticularly the fluid-filled chambers, are disclosed with reference tofootwear having a configuration that is suitable for running. Theinvention is not solely limited to footwear designed for running,however, and may be applied to a wide range of athletic footwear styles,including basketball shoes, cross-training shoes, walking shoes, tennisshoes, soccer shoes, and hiking boots, for example. In addition, theinvention may also be applied to non-athletic footwear styles, includingdress shoes, loafers, sandals, and work boots. Accordingly, one skilledin the relevant art will appreciate that the concepts disclosed hereinapply to a wide variety of footwear styles, in addition to the specificstyle discussed in the following material and depicted in theaccompanying figures.

First Chamber

An article of footwear 10 is depicted in FIG. 1 and includes an upper 20and a sole structure 30. Upper 20 has a substantially conventionalconfiguration and includes a plurality elements, such as textiles, foam,and leather materials, that are stitched or adhesively bonded togetherto form an interior void for securely and comfortably receiving thefoot. Sole structure 30 is positioned below upper 20 and includes twoprimary elements, a midsole 31 and an outsole 32. Midsole 31 is securedto a lower surface of upper 20, through stitching or adhesive bondingfor example, and operates to attenuate forces and absorb energy as solestructure 30 contacts the ground. That is, midsole 31 is structured toprovide the foot with cushioning during walking or running, for example.Outsole 32 is secured to a lower surface of midsole 31 and is formed ofa durable, wear-resistant material that engages the ground. In addition,sole structure 30 may include an insole, which is a thin cushioningmember, located within the void and adjacent to the foot to enhance thecomfort of footwear 10.

Midsole 31 is primarily formed of a polymer foam material, such aspolyurethane or ethylvinylacetate, that encapsulates a fluid-filledchamber 40. As depicted in FIGS. 2 and 3, chamber 40 is positioned in aheel region of midsole 31, which corresponds with the area of highestinitial load during footstrike. Chamber 40 may, however, be positionedin any region of midsole 31 to obtain a desired degree of cushioningresponse. Furthermore, midsole 31 may include multiple fluid-filledchambers having the general configuration of chamber 40.

Chamber 40 is depicted as having the structure of a bladder, whereinsealed layers of polymeric material enclose a fluid. Alternately,chamber 40 may be formed as a void within midsole 31. That is, materialhaving the shape of chamber 40 may be absent from midsole 31, therebyforming chamber 40.

In comparison with chambers of the prior art, chamber 40 and itsarrangement in the foam material of midsole 31 produces a relativelylarge deflection for a given load during initial stages of compression.As the compression of chamber 40 increases, however, the stiffness ofchamber 40 increases in a corresponding manner. This response tocompression, which will be described in greater detail in the followingmaterial, is due to the structure of chamber 40 and the manner in whichchamber 40 is incorporated into midsole 31. In general, the structure ofchamber 40 may be characterized as a single chamber, fluid-filledbladder. More particularly, chamber 40 has a central area 41 surroundedby five lobes 42 a-42 e that each have a distal end 43 a-43 e,respectively, as depicted in FIGS. 4-7. Lobes 42 a-42 e extend radiallyoutward from central area 41. Accordingly, lobes 42 a-42 e may extendoutward in different directions from a periphery of central area 41. Incombination with the foam material of midsole 31, which fills the spacesbetween lobes 42 a-42 e, midsole 31 provides an appropriate ratio of airto foam in specific areas under the heel of the foot.

For purposes of reference, a longitudinal axis 44 is depicted in FIGS.6A and 7 as extending through central area 41 and lobe 42 c. Chamber 40is symmetrical about a plane that extends through axis 44 and isgenerally perpendicular to the plane of FIGS. 6A and 7, while otherwisebeing asymmetrical. Accordingly, the structure of chamber 40 generallyresembles the shape of an oak leaf. Chamber 40 also includes a firstsurface 45, an opposite second surface 46, and a sidewall 47 thatextends between first surfaces 45 and 46. Both first surface 45 andsecond surface 46 have a generally planar configuration and areuniformly spaced apart from each other. First surface 45 has the generalshape of second surface 46, but with a reduced area. Accordingly,sidewall 47 slopes in the area between the individual lobes 42 a-42 e.For example, the slope of sidewall 47 may be approximately 40 degreesadjacent to central area 41, approximately 80 degrees adjacent to distalends 43 a-43 e, and gradually changing from 40 degrees to 80 degrees inthe area between. At the position of distal ends 43 a-43 e, however,sidewall 47 has a substantially vertical slope of 90 degrees. Sidewall47 may have a substantially planar configuration that forms an anglewith respect to first surface 45, or sidewall 47 may be curved.

The specific configuration of midsole 31 and the orientation of chamber40 may vary within the scope of the invention. When encapsulated by thepolymer foam material in midsole 31, for example, a portion of distalends 43 a-43 e may extend to an edge 33 of midsole 31, and may extendthrough edge 33 such that they are visible from the exterior of footwear10. Furthermore, first surface 45 may be coextensive with the plane ofthe upper surface of midsole 31 such that the heel engages first surface45. Alternately, chamber 40 may be entirely embedded within the foammaterial of midsole 31, or may be positioned with second surface 46being coextensive with the plane of the upper surface of midsole 31. Asdepicted in FIGS. 1-3, however, distal ends 43 a-43 e do not extendthrough edge 33 and second surface 46 is positioned adjacent a lowersurface of midsole 31. This configuration places a portion of the foammaterial in midsole 31 between the foot and first surface 45.

The slope of sidewall 47, which is depicted in the cross-sectional viewsof FIGS. 6B-6D, varies around chamber 40 to provide a smooth transitionfrom chamber 40 to the polymer foam material of midsole 31 duringcompression. As discussed above, sidewall 47 slopes from approximately40 degrees to 80 degrees between adjacent lobes 42 a-42 e and has asubstantially vertical slope at distal ends 43 a-43 e. The spacesbetween adjacent lobes 42 a-42 e have a generally U-shaped configurationin plan view, which is created by a curved surface of sidewall 47. Theportion of sidewall 47 positioned between adjacent lobes 42 a-42 e has aslope that is greater in areas adjacent to distal ends 43 a-43 e than inareas adjacent to central area 41. More specifically, sidewall 47 has arelatively shallow slope adjacent to central area 41, which correspondswith the rounded portion of the U-shaped configuration. As sidewall 47extends between central area 41 and distal ends 43 a-43 e, the slopeincreases. At distal ends 43 a-43 e, however, the slope of sidewall 47is substantially vertical. In other embodiments of the presentinvention, however, the slope of sidewall 47 may differ from thespecific configuration discussed herein to provide different degrees oftransition during compression.

The slopes of sidewall 47 between the various lobes 42 a-42 e areinversely matched by the resilient foam material of midsole 31.Accordingly, midsole 31 has a configuration with a plurality of columns34 that are formed of the foam material and extend between lobes 42 a-42e to contact the various areas of sidewall 47. The height of each column34 increases from positions adjacent to first surface 45 to positionsadjacent to second surface 46, and each column 34 slopes in a mannerthat corresponds with sidewall 47. Furthermore, due to the increasingspacing between lobes 42 a-42 e as they extend radially outward fromcentral area 42, the width of each column 43 increases accordingly.

A variety of materials may be utilized to form first surface 45, secondsurface 46, and sidewall 47, including the polymeric materials that areconventionally utilized in forming the outer layers of fluid-filledchambers for footwear, as discussed in the Background of the Inventionsection. In contrast with a majority of the prior art chamberstructures, however, the fluid within chamber 40 is at ambient pressureor at a pressure that is slightly elevated from ambient. Accordingly,the pressure of the fluid within chamber 40 may range from a gaugepressure of zero to over five pounds per square inch. Due to therelatively low pressure within chamber 40, the materials utilized toform first surface 45, second surface 46, and sidewall 47 need notprovide the barrier characteristics that operate to retain therelatively high fluid pressures of prior art chambers. Accordingly, awide range of polymeric materials such as thermoplastic urethane may beutilized to form first surface 45, second surface 46, and sidewall 47,and a variety of fluids such as air may be utilized within chamber 40.Furthermore, the wide range of polymeric materials may be selected basedupon the engineering properties of the material, such as the dynamicmodulus and loss tangent, rather than the ability of the material toprevent the diffusion of the fluid contained by chamber 40. When formedof thermoplastic polyurethane, first surface 45, second surface 46, andsidewall 47 may have a thickness of approximately 0.040 inches, but thethickness may range, for example, from 0.018 inches to 0.060 inches.

The relatively low pressure of the fluid within chamber 40 also providesanother difference between chamber 40 and prior art chambers. Therelatively high pressure in prior art chambers often requires theformation of internal connections between the polymer layers to preventthe chamber from expanding outward to a significant degree. That is,internal connections were utilized in prior art chambers to controloverall thickness of the chambers. In contrast, chamber 40 does not haveinternal connections between first surface 45 and second surface 46.

Chamber 40 may be manufactured through a variety of manufacturingtechniques, including blow molding, thermoforming, and rotationalmolding, for example. With regard to the blow molding technique,thermoplastic material is placed in a mold having the general shape ofchamber 40 and pressurized air is utilized to induce the material tocoat surfaces of the mold. In the thermoforming technique, layers ofthermoplastic material are placed between corresponding portions of amold, and the mold is utilized to compress the layers together atperipheral locations of chamber 40. A positive pressure may be appliedbetween the layers of thermoplastic material to induce the layers intothe contours of the mold. In addition, a vacuum may be induced in thearea between the layers and the mold to draw the layers into thecontours of the mold. In the rotational molding technique, thermoplasticmaterial is placed in a mold that subsequently rotates to induce thethermoplastic material to coat surfaces of the mold.

Chamber 40 and its arrangement in the foam material of midsole 31produces a relatively large deflection for a given load during initialstages of compression when compared to the fluid-filled chambersdiscussed in the Background of the Invention section. As the compressionof chamber 40 increases, however, the stiffness of chamber 40 increasesin a corresponding manner due to the structure of chamber 40 and themanner in which chamber 40 is incorporated into midsole 31. Threephenomena operate simultaneously to produce the effect described aboveand include pressure ramping, the properties of the foam material inmidsole 31, and film tensioning. Each of these phenomena will bedescribed in greater detail below.

Pressure ramping is the increase in pressure within chamber 40 thatoccurs as a result of compressing chamber 40. In effect, chamber 40 hasan initial pressure and initial volume when not being compressed withinmidsole 31. As midsole 31 is compressed, however, the effective volumeof chamber 40 decreases, thereby increasing the pressure of the fluidwithin chamber 40. The increase in pressure operates to provide aportion of the cushioning response of midsole 31.

The properties of the foam material also affect the cushioning responseof midsole 31, and will be discussed in terms of the configuration ofthe foam material and the hardness of the foam material. With regard tothe configuration, the foam material in midsole 31, which may have ahardness of 50-90 on the Asker C scale, for example, is concentratedadjacent edge 33 and is less prevalent in areas corresponding with thecenter of chamber 40. A change in the number of lobes 42 a-42 e may beutilized, for example, to decrease the ratio of air to foam inperipheral portions of midsole 31. This type of change in midsole 31 maybe utilized to increase the overall stiffness of midsole 31 duringcompression. Accordingly, the geometry of the foam material and thecorresponding geometry of chamber 40 have an effect upon the cushioningresponse.

Finally, the concept of film tensioning has an effect upon thecushioning response. This effect is best understood when compared topressurized prior art chambers. In the prior art chambers, the pressurewithin the chambers places the outer layers in tension. As the prior artchambers are compressed, however, the tension in the outer layers isrelieved or lessened. Accordingly, compression of the prior art chambersoperates to lessen the tension in the outer layers. In contrast with thepressurized prior art chambers, the tension in first surface 45increases in response to compression due to bending of first surface 45.This increase in tension contributes to the cushioning responsediscussed above. In applications where chamber 40 is rotated such thatsecond surface 46 is positioned adjacent the foot, the tension in secondsurface 46 will increases in response to compression, therebycontributing to the cushioning response

Pressure ramping, the properties of the foam material, and filmtensioning operate together to attenuate forces. The specific effectthat pressure ramping, the properties of the foam material, and filmtensioning has upon the cushioning response varies based upon locationwith respect to chamber 40. At perimeter portions of chamber 40, whichcorresponds with the locations of distal ends 43 a-43 e, the propertiesof the foam material provides reduced compliance and, therefore,increases the corresponding stiffness. As the location tends towardcentral area 41, columns 34 taper and allow a relatively largedeflection, and the dominant phenomena that attenuate forces and absorbenergy are film tensioning and pressure ramping. One skilled in therelevant art will recognize, based upon the preceding discussion, thatthe specialized cushioning response of sole structure 30 is primarilyrelated to the general configuration of chamber 40 and the foam materialof midsole 31 disclosed herein.

Based upon the considerations of pressure ramping, the properties of thefoam material, and film tensioning, the cushioning response of midsole31 is modifiable to provide a desired degree of force attenuation andenergy absorption. For example, the volume of chamber 40, the number andshape of lobes 42 a-42 e, the slope of sidewall 47, the thickness ofsurfaces 45 and 46, the material utilized to form the exterior ofchamber 40, and the position and orientation of chamber 40 withinmidsole 31 may be varied to modify the cushioning response. In addition,the properties of the foam material, including the hardness andthickness, may also be adjusted to modify the cushioning response. Byvarying these and other parameters, therefore, midsole 31 may be customtailored to a specific individual or to provide a specific cushioningresponse during compression.

Second Chamber

Another embodiment of the present invention is depicted as footwear 10′in FIG. 8. Footwear 10′ includes an upper 20′ and a sole structure 30′.Upper 20′ has a substantially conventional configuration that forms aninterior void for securely and comfortably receiving the foot. Solestructure 30′ is positioned below upper 20′ and includes two primaryelements, a midsole 31′ and an outsole 32′. Midsole 31′ is secured to alower surface of upper 20′ and operates to attenuate forces and absorbenergy as sole structure 30′ contacts the ground. Outsole 32′ is securedto a lower surface of midsole 31′ and is formed of a durable,wear-resistant material that engages the ground. In addition, solestructure 30′ may include an insole, which is a thin cushioning member,located within the void and adjacent to the foot to enhance the comfortof footwear 10′. Accordingly, footwear 10′ is generally similar instructure to footwear 10 discussed above. A primary difference offootwear 10′, however, is the structure of midsole 31′, and morespecifically the structure of a chamber 40′ that is embedded within afoam material of midsole 31′.

Midsole 31′ is primarily formed of a polymer foam material, such aspolyurethane or ethylvinylacetate, and chamber 40′ is positioned withina heel area of midsole 31′, as depicted in FIGS. 9 and 10. Chamber 40′is depicted individually in FIGS. 11-15 and includes a central area 41′,seven lobes 42 a′-42 g′, and seven corresponding distal ends 43 a′-43g′. In addition, chamber 40′ includes an axis 44′ for purposes ofreference, a first surface 45′, a second surface 46′, and a sidewall47′. Chamber 40′ is symmetrical about a plane that extends through axis44′ and is generally perpendicular to the plane of first surface 45′ andsecond surface 46′, while otherwise being asymmetrical. Whereas chamber40 has surfaces 45 and 46 with a substantially planar configuration,first surface 45′ of chamber 40′ has a curved configuration. That is,portions of first surface 45′ adjacent to distal ends 43 a′-43 c′ and 43e′-43 g′ curve upward to form a rounded or concave structure. Incontrast, the portion of first surface 45′ on lobe 42 d′ has asubstantially flat configuration.

With reference to FIGS. 9 and 10, the position of chamber 40′ in midsole31′ is depicted. In general, chamber 40′ is positioned such that secondsurface 46′ is coextensive with a lower surface of the foam material inmidsole 31′. This configuration places a portion of the foam material inmidsole 31′ between the foot and first surface 45′. Distal ends 43 a′-43c′ and 43 e′-43 g′ are also coextensive with an edge 33′ of midsole 31′.Accordingly, distal ends 43 a′-43 c′ and 43 e′-43 g′ are visible from anexterior of footwear 10′. Due to the curved configuration of secondsurface 46′, lobes 42 a′-42 c′ and 42 e′-42 g′ increase in height andvolume as they radiate outward from central area 41′ to distal ends 43a′-43 c′ and 43 e′-43 g′. The increase in volume permits a greatervolume of fluid to migrate from central area 41′ to distal ends 43 a′-43c′ and 43 e′-43 g′ during compression, thereby providing a more gradualtransition from a relatively compliant cushioning response to arelatively stiff cushioning response. Furthermore, the increase involume at the distal ends 43 a′-43 c′ and 43 e′-43 g′ reduces theoverall fluid pressure within chamber 40′ for a given degree ofcompression.

The slope of sidewall 47′, which is depicted in the cross-sectionalviews of FIGS. 13B-13D, varies around chamber 40′ to provide a smoothtransition during compression. Sidewall 47 slopes between adjacent lobes42 a′-42 g′ and has a substantially vertical slope at distal ends 43a′-43 e′. The spaces between adjacent lobes 42 a′-42 g′ have a generallyU-shaped configuration, which is created by a curved surface of sidewall47′. The portion of sidewall 47′ positioned between adjacent lobes 42a′-42 g′ has a slope that is greater in areas adjacent to distal ends 43a′-43 g′ than in areas adjacent to central area 41′. More specifically,sidewall 47′ has a relatively shallow slope adjacent to central area41′, which corresponds with the rounded portion of the U-shapedconfiguration. As sidewall 47′ extends between central area 41′ anddistal ends 43 a′-43 e′, the slope increases. At distal ends 43 a′-43e′, however, the slope of sidewall 47′ is substantially vertical.

The typical motion of the foot during running proceeds as follows:First, the heel strikes the ground, followed by the ball of the foot. Asthe heel leaves the ground, the foot rolls forward so that the toes makecontact, and finally the entire foot leaves the ground to begin anothercycle. During the time that the foot is in contact with the ground androlling forward, it also rolls from the outside or lateral side to theinside or medial side, a process called pronation. While the foot is airborne and preparing for another cycle the opposite process, calledsupination, occurs. Chamber 40 complements the motion of the foot duringrunning by providing central area 41 with greater compliance than areascorresponding with lobes 42 a-42 e, thereby resisting rolling of thefoot toward the medial side. In further embodiments, the size of lobes42 a-42 e and the properties or quantity of the foam material may bealtered to limit pronation. Similar concepts also apply to chamber 40′.

As with chamber 40, chamber 40′ and its arrangement in the foam materialof midsole 31′ produces a relatively large deflection for a given loadduring initial stages of compression when compared to the fluid-filledchambers discussed in the Background of the Invention section. As thecompression of chamber 40′ increases, however, the stiffness of chamber40′ increases in a corresponding manner due to the structure of midsole31. This effect is also the result of pressure ramping, the propertiesof the foam material in midsole 31′, and film tensioning. Accordingly,the volume of chamber 40′, the number and shape of lobes 42 a′-42 g′,the slope of sidewall 47′, the thickness of surfaces 45′ and 46′, thematerial utilized to form the exterior of chamber 40′, and the positionand orientation of chamber 40′ within midsole 31′ may be varied tomodify the cushioning response. In addition, the properties of the foammaterial, including the amount of foam material and the hardness andthickness, may also be adjusted to modify the cushioning response. Byvarying these and other parameters, therefore, midsole 31′ may be customtailored to a specific individual or to provide a specific cushioningresponse during compression.

One structural difference between chamber 40 and chamber 40′ relates tothe curved configuration of first surface 45′. With the curvedconfiguration, the effect that film tensioning has upon the cushioningresponse occurs more rapidly during compression due to the downwardangle of first surface 45′. That is, for a given degree of deflection inchamber 40′, the effect of film tensioning will have a greater effectupon the cushioning characteristics when first surface 45′ is curved.Furthermore, the curved configuration permits chamber 40′ to have afluid volume that is greater than the fluid volume of chamber 40, butwith approximately the same stiffness.

Chamber 40 and chamber 40′ were discussed in the above material toprovide examples of the many chamber configurations that fall within thescope of the present invention. In general, an chamber will have a pairof opposite surface that form lobes in the chamber. Chamber 40 andchamber 40′ were disclosed as having five and seven lobes, respectively.In other embodiments, however, the chambers may have any number of lobesranging from three to twenty, for example.

Manufacturing Method

A method of manufacturing chamber 40′ through a blow molding processwill now be discussed with reference to FIGS. 16-25. In a conventionalblow molding process for forming footwear chambers, a generally hollowand tubular structure of molten polymer material, otherwise referred toas a parison, is positioned between corresponding portions of a mold.The mold is then closed upon the parison such that a portion of themolten polymer material is drawn into the mold and conforms to the shapeof the mold. Finally, the mold compresses opposite sides of the parisontogether and forms a bond between the opposite sides. In some blowmolding process, however, an inlet remains open such that a pressurizedfluid may be injected at a later stage of the manufacturing process,with the inlet being subsequently sealed.

The conventional blow molding process described above commonly utilizesa mold having two corresponding mold portions. Each mold portion has agenerally planar surface and a recess that is formed in the surface,with the shape of the recess corresponding to one-half of the shape ofthe chamber. Accordingly, closing the mold portions forms a cavitywithin the mold with the shape of the chamber.

One consequence of the conventional mold structure is that the parisonmust stretch in order to extend into the recesses, and the stretchingdecreases the overall thickness of the parison wall. In order tocounteract the effects of stretching, the parison is generally formedwith an initial wall thickness that will stretch to the desired, lesserwall thickness. This manner of counteracting the effects of stretchingis appropriate when the mold geometry is such that the parison stretchesin a generally uniform manner. When the mold geometry is such that theblow-up ratio of some portions of the parison stretch is more than theblow-up ratio of other portions, however, merely increasing the wallthickness of the parison may not be appropriate due the resultingvariance in the wall thickness of the chamber.

Conventional mold portions with generally planar surfaces and recessesthat form a cavity with the shape of chamber 40′ would generally be ofthe type that would cause specific portions of the parison to stretchsubstantially more than other portions. For example, the portion of theparison forming the area of chamber 40′ where distal ends 43 a′-43 g′join with first surface 45′ would stretch substantially more than theportion of the parison forming central area 41′. Accordingly, thethickness of chamber 40′ at the junction of distal ends 43 a′-43 g′ andfirst surface 45′ would be substantially less than the thickness ofchamber 40′ at central area 41′. The method of manufacturing chamber40′, however, which is described below, provides a blow molding processthat forms each of first surface 45′, second surface 46′, and sidewall47′ to have a substantially uniform thickness.

Another consequence of the conventional mold structure is that a partingline is formed in a middle of a sidewall of the resulting chamber. Asdiscussed above, the mold compresses opposite sides of the parisontogether and forms a bond between the opposite sides. The bondrepresents the parting line and corresponds with the area where theopposite mold portions meet. In some footwear applications, the sidewallof the chamber is visible. A parting line positioned in a middle of thesidewall would, therefore, detract from the aesthetic properties of thechamber. The method of manufacturing chamber 40′, however, provides ablow molding process that positions the parting line away from themiddle of sidewall 47′, and particularly from areas corresponding withdistal ends 43 a′-43 g′.

A mold 100 that may be utilized to form chamber 40′ is depicted in FIGS.16-18. Mold 100 includes a first mold portion 110 and a correspondingsecond mold portion 120. When joined together, mold portions 110 and 120form a cavity having dimensions substantially equal to the exteriordimensions of chamber 40′. Unlike the conventional mold for formingfootwear chambers through a blow molding process, mold portions 110 and120 do not have generally planar surfaces adjacent to the cavity thatforms chamber 40′. Instead, first mold portion 110 defines a pluralityof indentations 111 a-c and 111 e-g, and second mold portion 120 definesa plurality of protrusions 121 a-c and 121 e-g, as depicted in FIG. 16.

First mold portion 110 is depicted individually in FIG. 17 and forms theportions of chamber 40′ corresponding with first surface 45′ and theareas of sidewall 47′ positioned adjacent to central area 41′. Firstmold portion 110 also forms that area of sidewall 47′ corresponding withdistal end 43 d′. A ridge 112 extends around a centrally-located area offirst mold portion 110. As will be discussed in greater detail below,ridge 112 is partially responsible for forming a parting line in chamber40′. Accordingly, the area of first mold portion 110 located within thearea bounded by ridge 112 forms first surface 45′ and portions ofsidewall 47′. More specifically, the surface of first mold portion 110generally located proximal to a central area 113 forms central area 41′,surfaces generally located around a plurality of lobe areas 114 a-114 gform the portions of lobes 42 a′-42 g′ on first surface 45′, andsurfaces generally located around sidewall areas 115 a-115 g form theportions of sidewall 47′ positioned adjacent to central area 41′.

The portions of first surface 45′ adjacent to distal ends 43 a′-43 c′and 43 e′-43 g′ curve upward to form a rounded or concave structure, asdiscussed with reference to chamber 40′. In order to form thisconfiguration, the area of first mold portion 110 located within thearea bounded by ridge 112 has a corresponding convex configuration.Accordingly, the surface of first mold portion 110 has a curvedconfiguration from central area 113 to sidewall areas 114 a-c and 114e-g.

An extension of ridge 112 extends outward from sidewall area 114 d andforms an L-shaped channel 116. As discussed in greater detail below,channel 116 is utilized to form a conduit through which a fluid may beinjected into chamber 40′. Another feature of first mold portion 110 isa plurality of slot vents 117 distributed throughout central area 113and sidewall areas 114 a-114 g. Slot vents 117 provide outlets for airas a parison is drawn into first mold portion 110 during the formationof chamber 40′.

Second mold portion 120 is depicted individually in FIG. 18 and formsthe portions of chamber 40′ corresponding with second surface 46′ andthe areas of sidewall 47′ corresponding with distal ends 43 a′-43 c′ and43 e′-43 g′. A ridge 122 extends around a centrally-located area ofsecond mold portion 120, and ridge 122 cooperatively forms the partingline in chamber 40′ with ridge 112. When first mold portion 110 isjoined with second mold portion 120, therefore, ridge 112 is positionedimmediately adjacent to ridge 122. The area of second mold portion 120located within the area bounded by ridge 122 forms second surface 46′and the areas of sidewall 47′ corresponding with distal ends 43 a′-43 c′and 43 e′-43 g′. More specifically, the surface of second mold portion120 generally located proximal to a central area 123 forms central area41′, surfaces generally located around a plurality of lobe areas 124a-124 g form the portions of lobes 42 a′-42 g′ on second surface 46′,and surfaces generally located around distal areas 125 a-c and 125 e-gform the portions of sidewall 47′ corresponding with distal ends 43a′-43 c′ and 43 e′-43 g′.

With reference to chamber 40′, second surface 46′ has a generally planarconfiguration. The area of second mold portion 120 corresponding withcentral area 123 and lobe areas 124 a-124 g, which forms second surface46′, also has a generally planar configuration. Distal areas 125 a-c and125 e-g extend upward from lobe areas 124 a-c and 124 e-g, respectively,to provide a generally planar area for forming distal ends 43 a′-43 c′and 43 e′-43 g′. An extension of ridge 122 extends outward from lobearea 124 d and forms an L-shaped channel 126. In combination withchannel 116, a conduit is formed through which a fluid may be injectedinto chamber 40′. Second mold portion 120 also includes a plurality ofslot vents 127, which are distributed throughout central area 123 andlobe areas 124 a-124 g. As with slot vents 117, slot vents 127 provideoutlets for air as the parison is drawn into second mold portion 120during the formation of chamber 40′.

Indentations 111 a-c and 111 e-g and protrusions 121 a-c and 121 e-gextend outward from the portions of mold portions 110 and 120 that formchamber 40′. More specifically, indentations 111 a-c and 111 e-g extendradially outward from lobe areas 114 a-c and 114 e-g, respectively.Similarly, protrusions 121 a-c and 121 e-g extend radially outward fromlobe areas 124 a-c and 124 e-g, respectively. Accordingly, indentations111 a-c and 111 e-g and protrusions 121 a-c and 121 e-g are generallyaligned with the portions of mold 100 that form lobes 42 a′-42 c′ and 42e′-42 g′.

The manner in which mold 100 is utilized to form chamber 40′ from aparison 130 will now be discussed. Parison 130 is a generally hollow andtubular structure of molten polymer material. As utilized herein, theterm tubular is not limited to a cylindrical configuration, which has acircular cross-section, but is also intended to encompass configurationshaving an elongated or oblong cross-section. In forming parison 130, themolten polymer material is extruded from a die. The wall thickness ofparison 130 may be substantially constant, or may vary around theperimeter of parison 130. Accordingly, a cross-sectional view of parison130 may exhibit areas of differing wall thickness. Suitable materialsfor parison 130 include the materials discussed above with respect tochamber 40 and chamber 40′.

Following the formation of parison 130, as described above, parison 130is suspended between mold portions 110 and 120, as depicted in FIG. 19.For purposes of discussion, parison 130 has a first side 131 that facesfirst mold portion 110, and parison 130 has a second side 132 that facessecond mold portion 120. Mold portions 110 and 120 are then aligned suchthat indentations 111 a-c and 111 e-g correspond with protrusions 121a-c and 121 e-g, respectively. In this position, the areas of moldportions 110 and 120 that form chamber 40′ are positioned on oppositesides of parison 130 and are also aligned. Mold portions 110 and 120then translate toward each other such that mold 100 contacts parison130, as depicted in FIG. 20. More specifically, the surfaces of firstmold portion 110 in which indentations 111 a-c and 111 e-g are formedcontact first side 131, and the surfaces of second mold portion 120 thatform protrusions 121 a-c and 121 e-g contact second side 132.

When mold 100 contacts parison 130, portions of parison 130 bend toaccommodate further movement of mold portions 110 and 120 toward eachother, which is also depicted in FIG. 20. In particular, first surface131 bends into indentations 111 a-c and 111 e-g, and second surface 132bends around protrusions 121 a-c and 121 e-g. Accordingly, parison 130continues to bend as mold portions 110 and 120 continue to translatetoward each other.

Upon further movement of mold portions 110 and 120 toward each other,protrusions 121 a-c and 121 e-g extend entirely into indentations 111a-c and 111 e-g and side 131 of parison 130 is compressed against side132 of parison 130, thereby bonding portions of side 131 to side 132, asdepicted in FIG. 21. A central area of parison 130, however, contactsand conforms to the surfaces of mold 100 that are intended to formchamber 40′. Accordingly, a central area of first side 131 contacts andconforms to the contours of central area 113, lobe areas 114 a-114 g,and sidewall areas 115 a-115 g. Similarly, a central area of second side132 contacts and conforms to the contours of central area 123, areaslobe 124 a-124 g, and distal areas 125 a-c and 125 e-g. Furthermore,ridges 112 and 122 compress sides 131 and 132 together, thereby forminga bond that seals peripheral areas of chamber 40′.

As mold 100 closes, a fluid, such as air, having a positive pressure incomparison with ambient air may be injected between sides 131 and 132 toinduce parison 130 to contact and conform to the contours of moldportions 110 and 120. Initially, the fluid may be delivered from the diemechanism that forms parison 130 and may be directed along thelongitudinal length of parison 130, thereby preventing sides 131 and 132from contacting each other. Once mold 100 closes upon parison 130,however, the fluid may be directed through the conduit formed bychannels 116 and 126. For example, a needle may puncture parison 130 atthe entrance to the conduit and deliver a fluid that travels down theconduit and into the area forming chamber 40′. Air may also be removedfrom the area between parison 130 and mold portions 110 and 120 throughslot vents 117 and 127, thereby drawing parison 130 onto the surface ofmold portions 110 and 120.

Once chamber 40′ is formed within mold 100, mold portions 110 and 120separate such that the parison may be removed from mold 100, as depictedin FIGS. 23-24. The polymer material forming parison 130 is thenpermitted to cool, and the conduit formed by channels 116 and 126 may besealed to enclose the fluid within chamber 40′ at ambient pressure.Alternately, a pressurized fluid may be injected through the conduitprior to sealing. In addition, excess portions of parison 130 may betrimmed or otherwise removed from chamber 40′. The excess portions maythem be recycled or reutilized to form another parison.

Based upon the above discussion, mold portions 110 and 120 eachgenerally include a bending zone and a forming zone that have differentfunctions. With respect to first mold portion 110, the bending zoneincludes indentations 111 a-c and 111 e-g. The bending zone isresponsible, therefore, for bending parison 130 prior to bonding. Theforming zone includes central area 113, lobe areas 114 a-114 g, andsidewall areas 115 a-115 g. The forming zone is responsible, therefore,for imparting the actual shape of chamber 40′ to the parison. That is,the forming zone actually forms first surface 45′ and portions ofsidewall 47′ of chamber 40′. Similarly, bending zone of second moldportion 120 includes protrusions 121 a-c and 121 e-g and is alsoresponsible for bending parison 130 prior to bonding. The forming zoneof second mold portion 120 includes central area 123, lobe areas 124a-124 g, and distal areas 125 a-c and 125 e-g, and the forming zoneactually forms second surface 46′ and other portions of sidewall 47′.Accordingly, mold portions 110 and 120 each include a bending zone thatbends the parison and a forming zone that forms portions of chamber 47′,the bending zone being separate from the forming zone.

Sides 131 and 132 bend when mold portions 110 and 120 initially contactparison 130, as discussed above. Some portions of parison 130 maystretch, however, in order to induce parison 130 to contact and conformto the various surfaces that form chamber 40′. The purpose of bendingsides 131 and 132 when mold portions 110 and 120 initially contactparison 130 is to impart a uniformity to the stretching of parison 130.That is, the bending of parison 130 ensures that sides 131 and 132stretch in a generally uniform manner, thereby imparting a largelyuniform thickness to first surface 45′, second surface 46′, and sidewall47′ of chamber 40′.

Another advantage of bending sides 131 and 132 relates to a position ofa parting line 133, which corresponds with the area where the oppositemold portions meet adjacent to bladder 40′. That is, parting line 133 isthe bond in chamber 40′ between side 131 and side 132 that is formed byridges 112 and 122. Referring to FIG. 26, the position of parting line133 is highlighted with a dashed line for purposes of reference. In manyprior art chambers formed through a conventional blow molding process,the parting line extends horizontally across the sidewall in a linearmanner and obscures portions of the sidewall. With regard to chamber40′, however, parting line 133 does not merely extend vertically acrosssidewall 47′. Instead, parting line 133 follows a non-linear coursehaving a wave-like pattern that extends around distal ends 43 a′-43 g′.More specifically, parting line 133 extends horizontally betweensidewall 47′ and first surface 45′ at upper ends of distal ends 43 a′-43c′ and 43 e′-43 g′. Parting line 133 then extends vertically acrosssidewall 47′ and along the sides of distal ends 43 a′-43 c′ and 43 e′-43g′. Accordingly, at least a portion of parting line 133 extends betweenfirst surface 45′ and second surface 46′. Parting line 133 also extendshorizontally between sidewall 47′ and second surface 46′ in areasbetween lobes 42 a′-42 g′. When incorporated into an article offootwear, as depicted in FIG. 8, parting line 133 will generally not bevisible, and parting line 133 will not extend across distal ends 43a′-43 g′, which are the visible portions of chamber 40′. Parting line133 is, therefore, not centered in sidewall 47′.

One consequence of the non-linear parting line 133 is that specificareas of sidewall 47′ are formed from either first side 131 or secondside 132. For example, the areas of sidewall 47′ that are adjacent tocentral area 41′, which will be referred to as first areas herein, areformed by first side 131. Accordingly, the first area of sidewall 47′extends from first surface 45′ to second surface 46′ and is formed fromfirst side 131. Similarly, the areas of sidewall 47′ that form distalends 43 a′-43 c′ and 43 e′-43 g′, which will be referred to as secondareas herein, are formed from second side 132. Accordingly, the secondarea of sidewall 47′ also extends from first surface 45′ to secondsurface 46′ and is formed from second side 132. In general, the firstarea and the second area alternate such that the first side and thesecond side are interlaced to form sidewall 47′.

The blow molding method described above departs from the conventionalblow molding process for footwear chambers. For example, mold 100includes the plurality of indentations 111 a-c and 111 e-g and theplurality of protrusions 121 a-c and 121 e-g to bend parison 130 priorto bonding or stretching, thereby inducing uniformity in the wallthickness of chamber 40′. In addition, the bending of parison 130 formsa non-centered parting line 133 that does not extend across visibleportions of sidewall 47′.

Third Chamber

Another configuration of footwear 10′ is depicted in FIGS. 26 and 27 ashaving both chamber 40′ and an additional fluid-filled chamber 40″.Whereas chamber 40′ is located in the heel area of midsole 31′, chamber40″ is located in a forefoot area of midsole 31′. Accordingly, chamber40′ and chamber 40″ respectively provide force attenuation to the heeland forefoot of the wearer. Chamber 40″ is depicted individually inFIGS. 28-33 and includes a first subchamber 41 a″, a second subchamber41 b″, a third subchamber 41 c″, seven lobes 42 a″-42 g″, and sevencorresponding distal ends 43 a″-43 g″. In addition, chamber 40″ includesa pair of conduits 44 a″ and 44 b″, a first surface 45″, a secondsurface 46″, and a sidewall 47″.

Whereas chambers 40 and 40′ are suitable for use with either the leftfoot or right foot. The configuration of chamber 40″ depicted in FIGS.28-33 has an asymmetrical configuration and is most suitable for usewith the left foot, as discussed in greater detail below. Accordingly,chamber 40″ may be manufactured to have a substantially identical, butreversed, configuration that is most suitable for use with the rightfoot, as depicted in FIG. 34. Depending upon the particular style offootwear 10′ and the intended use of footwear 10′, either configurationof chamber 40″ may be utilized in footwear 10′. That is, eitherconfiguration of chamber 40″ may be utilized in footwear that isintended for either the left foot or the right foot.

Subchambers 41 a″-41 c″ form a majority of the volume of chamber 40″ andare fluidly-connected by conduits 44 a″ and 44 b″. More particularly,conduit 44 a″ extends between first subchamber 41 a″ and secondsubchamber 41 b″ to permit fluid flow between subchambers 41 a″ and 41b″. Similarly, conduit 44 b″ extends between second subchamber 41 b″ andthird subchamber 41 c″ to permit fluid flow between subchambers 41 b″and 41 c″. If first subchamber 41 a″ is compressed, the fluid withinfirst subchamber 41 a″ may pass through conduit 44 a″ and into secondsubchamber 41 b″, and a portion of the fluid within second subchamber 41b″ may pass through conduit 44 b″ and into third subchamber 41 c″. Ifthird subchamber 41 c″ is compressed, the fluid within third subchamber41 c″ may pass through conduit 44 b″ and into second subchamber 41 b″,and a portion of the fluid within second subchamber 41 b″ may passthrough conduit 44 a″ and into first subchamber 41 a″. Similarly, ifsecond subchamber 41 b″ is compressed, the fluid within secondsubchamber 41 b″ may pass through both of conduits 44 a″ and 44 b″ andinto each of subchambers 41 a″ and 41 c″. Accordingly, subchambers 41a″-41 c″ are in fluid communication with each other through conduits 44a″ and 44 b″. In some configurations of chamber 40″, valves may belocated within conduits 44 a″ and 44 b″ to limit fluid flow betweensubchambers 41 a″-41 c″, or one or both of conduits 44 a″ and 44 b″ maybe sealed to prevent fluid flow.

Subchambers 41 a″-41 c″ form each enclose a portion of the fluid withinchamber 40″. Although the relative volume of fluid within subchambers 41a″-41 c″ may vary significantly within the scope of the presentinvention, chamber 40″ is depicted as having a configuration withinfirst subchamber 41 a″ has a greater volume than both of subchambers 41b″ and 41 c″, and second subchamber 41 b″ has a greater volume thanthird subchamber 41 c″. As a comparison, first subchamber 41 a″ mayhave, for example, a volume that is approximately twice the volume ofsecond subchamber 41 b″, and second subchamber 41 b″ may have, forexample, a volume that is approximately twice the volume of thirdsubchamber 41 c″. In further configurations, chamber 40″ may exhibitsubstantially different ratios between the volumes of subchambers 41a″-41 c″. Furthermore, third subchamber 41 c″ may be significantlyreduced in size or absent from chamber 40″ in some configurations.

Subchambers 41 a″-41 c″ are arranged in a non-linear relationship,wherein second subchamber 41 b″ is located next to first subchamber 41a″, and third subchamber 41 c″ is located forward of second subchamber41 b″. More particularly, if an axis passed through each of subchambers41 a″ and 41 b″, then third subchamber 41 c″ would be spaced from thataxis. Similarly, if an axis passed through each of subchambers 41 b″ and41 c″, then first subchamber 41 a″ would be spaced from that axis. Ineffect, therefore, subchambers 41 a″-41 c″ form three points of atriangular pattern. As discussed in greater detail below, thisarrangement for subchambers 41 a″-41 c″ locates first subchamber 41 a″in a lateral portion of footwear 10′, and also locates subchambers 41 b″and 41 c″ in a medial portion of footwear 10′.

Lobes 42 a″-42 c″ extend outward from first subchamber 41 a″ and are influid communication with first subchamber 41 a″. If first subchamber 41a″ is compressed, as discussed above, a portion of the fluid withinfirst subchamber 41 a″ may also pass into lobes 42 a″-42 c″. Similarly,lobes 42 d″-42 f″ extend outward from second subchamber 41 b″ and are influid communication with second subchamber 41 b″, and lobe 42 g″ extendsoutward from third subchamber 41 c″ and is in fluid communication withthird subchamber 41 c″. In addition to passing through conduits 44 a″and 44 b″, fluid may pass into lobes 42 d″-42 g″ if either ofsubchambers 41 b″ and 41 c″ are compressed. The number and location oflobes 42 a″-42 g″ may vary significantly. In many configurations ofchamber 40″, however, each of subchambers 41 a″ and 41 b″ will generallyhave at least two of the lobes 42 a″-42 g″.

Distal ends 43 a″-43 g″ form end areas of lobes 42 d″-42 g″ and arelocated opposite subchambers 41 a″-41 c″, respectively. When chamber 40″is incorporated into footwear 10′, distal ends 43 a″-43 g″ may protrudethrough a sidewall of midsole 31′. More particularly, lobes 42 a″-42 c″may extend to a lateral side of footwear 10′ such that distal ends 43a″-43 c″ protrude through a sidewall of midsole 31′, and lobes 42 d″-42g″ may extend to an opposite medial side of footwear 10′ such thatdistal ends 43 d″-43 g″ protrude through an opposite portion of thesidewall of midsole 31′. In some configurations of footwear 10′,however, distal ends 43 a″-43 g″ may be wholly located within midsole31′, or distal ends 43 a″-43 g″ may protrude outward and beyond thesidewall of midsole 31′. In addition, distal ends 43 a″-43 g″ may beoriented substantially perpendicular to a plane on which the subchamber41 a″-41 c″.

First surface 45″ forms an upper surface of chamber 40″ and has a curvedconfiguration. That is, portions of first surface 45″ adjacent to distalends 43 a″-43 g″ curve upward to form a rounded or concave structure inthe upper area of chamber 40″. Second surface 46″ is located oppositefirst surface 45″ and has a generally planar configuration. In someconfigurations of footwear 10′, second surface 46″ may form the uppersurface of chamber 40″. In comparison with first surface 45″, secondsurface 46″ has a greater surface area. More particularly, secondsurface 46″ is depicted as having approximately twice as much surfacearea as first surface 45″, but may range from being substantially equalto having ten times as much surface area, for example. To account forthe differences in surface area, sidewall 47″ extends from a peripheryof first surface 45″ and slopes downward to a periphery of secondsurface 46″. In comparison with second surface 46″, which slopesdownward, distal ends 43 a″-43 g″ have a substantially verticalorientation.

As discussed above, the typical motion of the foot during runningincludes rolling from the outside or lateral side to the inside ormedial side, which is referred to as pronation. Chamber 40″ complementsthe motion of the foot during running through the relative locations ofthe various components of chamber 40″. First subchamber 41 a″ isgenerally located in a lateral portion of footwear 10′, and subchambers41 b″ and 41 c″ are generally located in a medial portion of footwear10′. In this configuration, at least a portion of first subchamber 41 a″and lobes 42 a″-42 c″ underlie the third, fourth, and fifthmetatarsophalangeal joints (i.e., the joints respectively between thethird, fourth, and fifth metatarsals and the third, fourth, and fifthproximal phalanges). Similarly, at least a portion of second subchamber41 b″ and lobes 42 d″-42 f″ underlie the first and secondmetatarsophalangeal joints (i.e., the joints respectively between thefirst and second metatarsals and the first and second proximalphalanges). In addition, at least a portion of third subchamber 41 c″and lobe 42 g″ underlie the first proximal phalanx and first distalphalanx (i.e., the big toe).

Based upon the positions of the various portions of chamber 40″discussed above, the foot may initially compress first subchamber 41 a″,which is located in the lateral portion of footwear 10′ during running.As first subchamber 41 a″ is compressed, the pressure of the fluidwithin first are 41 a″ increases and a portion of the fluid passesthrough conduit 44 a″ and into second subchamber 41 b″. This has theeffect of decreasing the compressibility of second subchamber 41 b″ andassists with inhibiting rolling of the foot from the lateral side to themedial side. As the foot rolls from the lateral side to the medial side,however, second subchamber 41 b″ is compressed and the fluid withinsecond subchamber 41 b″ passes through conduit 44 b″ and increases thepressure of the fluid within third subchamber 41 c″. This has the effectof decreasing the compressibility of third subchamber 41 c″ and assistswith pushing off, which occurs as the foot rolls forward and as the footis leaving the ground.

Another factor that affects the compressibility of chamber 40 and rollof the foot relates to the slope of sidewall 47″. Referring to FIGS.28-30, for example, the slope of sidewall 47″ associated with firstsubchamber 41 a″ is different in forward and rear areas. In the reararea of first subchamber 41 a″ the slope of sidewall 47″ is relativelyshallow, whereas the slope of sidewall 47″ is greater in the forwardarea of first subchamber 41 a″. The differences in slope affect thecompressibility of first subchamber 41 a″ and the degree to which thefoot rolls. More particularly, the shallower slope in the rear area offirst subchamber 41 a″ facilitates compression and roll of the foot. Asthe foot rolls forward and toward the forward area of first subchamber41 a″, the greater slope of sidewall 47″ inhibits compression of firstsubchamber 41 a″ and slows the roll of the foot. That is, areas of firstsubchamber 41 a″ with a relatively shallow slope (i.e., the rear area)are more compressible than areas of first subchamber 41 a″ with agreater slope (i.e., the forward area).

Differences in slope of sidewall 47″ are also present in secondsubchamber 41 b″ and third subchamber 41 c″. In second subchamber 41 b″,sidewall 47″ has a relatively shallow slope in areas that are adjacentto first subchamber 41 a″ and a greater slope in areas adjacent lobes 42d″-42 f. As with first subchamber 41 a″, areas of second subchamber 41b″ with a relatively shallow slope are more compressible than areas ofsecond subchamber 41 b″ with a greater slope. This facilitates roll ofthe foot toward second subchamber 41 b″, but limits further roll of thefoot toward the medial portion of footwear 10′. Similarly, thirdsubchamber 41 c″ has a configuration wherein sidewall 47″ is relativelysteep in areas adjacent to second subchamber 41 b″, but is more shallowin forward areas of third subchamber 41 c″, thereby facilitating pushingoff.

As with chambers 40 and 40′, chamber 40″ and its arrangement in the foammaterial of midsole 31′ produces a relatively large deflection for agiven load during initial stages of compression when compared to some ofthe fluid-filled chambers discussed in the Background of the Inventionsection. As the compression of chamber 40″ increases, however, thestiffness of chamber 40″ increases in a corresponding manner due to thestructure of midsole 31′. This effect is also the result of pressureramping, the properties of the foam material in midsole 31′, and filmtensioning. Accordingly, the volume of chamber 40″, the number and shapeof lobes 42 a″-42 g″, the slope of sidewall 47″, the thickness ofsurfaces 45″ and 46″, the material utilized to form the exterior ofchamber 40″, and the position and orientation of chamber 40″ withinmidsole 31′ may be varied to modify the cushioning response. Inaddition, the properties of the foam material, including the amount offoam material and the hardness and thickness, may also be adjusted tomodify the cushioning response. By varying these and other parameters,therefore, midsole 31′ may be custom tailored to a specific individualor to provide a specific cushioning response during compression.

A variety of materials may be utilized to form chamber 40″, includingthe polymeric materials that are conventionally utilized in forming theouter layers of fluid-filled chambers for footwear, as discussed in theBackground of the Invention section. In contrast with a majority of theprior art chamber structures, however, the fluid within chamber 40″ isat ambient pressure or at a pressure that is slightly elevated fromambient. Accordingly, the pressure of the fluid within chamber 40″ mayrange from a gauge pressure of zero to over five pounds per square inch.Due to the relatively low pressure within chamber 40″, the materialsutilized to form first surface 45″, second surface 46″, and sidewall 47″need not provide the barrier characteristics that operate to retain therelatively high fluid pressures of prior art chambers. Accordingly, awide range of polymeric materials such as thermoplastic urethane may beutilized to form first surface 45″, second surface 46″, and sidewall47″, and a variety of fluids such as air may be utilized within chamber40″. Furthermore, the wide range of polymeric materials may be selectedbased upon the engineering properties of the material, such as thedynamic modulus and loss tangent, rather than the ability of thematerial to prevent the diffusion of the fluid contained by chamber 40″.When formed of thermoplastic polyurethane, first surface 45″, secondsurface 46″, and sidewall 47″ may have a thickness of approximately 0.04inches, but the thickness may range, for example, from 0.01 inches to0.10 inches. Depending upon the materials utilized, thicknesses lessthan or exceeding this range may be utilized.

The relatively low pressure of the fluid within chamber 40″ alsoprovides another difference between chamber 40″ and prior art chambers.The relatively high pressure in prior art chambers often requires theformation of internal connections between the polymer layers to preventthe chamber from expanding outward to a significant degree. That is,internal connections were utilized in prior art chambers to controloverall thickness of the chambers. In contrast, chamber 40″ does nothave internal connections between first surface 45″ and second surface46″.

Fourth Chamber

Another article of footwear 200 is depicted in FIGS. 35 and 36 as havingan upper 220 and a sole structure 230. For reference purposes, footwear200 may be divided into three general regions: a forefoot region 211, amidfoot region 212, and a heel region 213, as depicted in FIGS. 35 and36. Footwear 200 also includes a lateral side 214 and an opposite medialside 215. Forefoot region 211 generally includes portions of footwear200 corresponding with the toes and the joints connecting themetatarsals with the phalanges. Midfoot region 212 generally includesportions of footwear 200 corresponding with the arch area of the foot,and heel region 213 corresponds with rear portions of the foot,including the calcaneus bone. Lateral side 214 and medial side 215extend through each of regions 211-213 and correspond with oppositesides of footwear 200. Regions 211-213 and sides 214-215 are notintended to demarcate precise areas of footwear 200. Rather, regions211-213 and sides 214-215 are intended to represent general areas offootwear 200 to aid in the following discussion. In addition to footwear200 generally, regions 211-213 and sides 214-215 may also be applied toupper 220, sole structure 230, and individual elements thereof.

Upper 220 has a substantially conventional configuration and includes aplurality elements, such as textiles, foam, and leather materials, thatare stitched or adhesively bonded together to form an interior void forsecurely and comfortably receiving the foot. In addition to theconfiguration depicted in the figures, upper 220 may have a variety ofother conventional or non-conventional configurations within the scopeof the invention. That is, the specific configuration of upper 220 mayvary considerably. Sole structure 230, which is depicted individually inFIGS. 37-40, is positioned below upper 220 and includes two primaryelements, a midsole 231 and an outsole 231′. Midsole 231 is secured to alower surface of upper 220 through stitching or adhesive bonding, forexample, and operates to attenuate forces as sole structure 230 contactsthe ground. That is, midsole 231 is structured to provide the foot withcushioning during walking or running. Midsole 231 may also control footmotions, such as pronation, during walking and running. Outsole 231′ issecured to a lower surface of midsole 231 and is formed of a durable,wear-resistant material that engages the ground and imparts traction. Inaddition, sole structure 230 may include an insole (not depicted), whichis a thin cushioning member located within the void in upper 220 andadjacent to a plantar (i.e., lower) surface of the foot to enhance thecomfort of footwear 200.

Midsole 231 includes a forward element 232, an upper heel element 233, alower heel element 234, and a chamber 240 positioned between heelelements 233 and 234. Forward element 232 extends through each ofregions 211 and 212 and is primarily formed of a polymer foam material,such as polyurethane or ethylvinylacetate, but may also be formed ofother materials. The specific configuration of forward element 232 mayvary significantly to include a variety of dimensions (e.g., length,width, thickness) and material properties (e.g., foam type and density).Forward element 232 may also encapsulate a fluid-filled chamber, such aschamber 40″ or a variety of other conventional or non-conventionalchambers. Although forward element 232 is depicted as extending betweenupper 220 and outsole 231′, other elements (e.g., plates or moderators)may be utilized in conjunction with forward element 232.

Heel elements 233 and 234 are primarily located within heel region 213and cooperatively shaped to receive chamber 240 and secure chamber 240within sole structure 230. Upper heel element 233 is shaped to conformwith the contours of an upper area of chamber 240 and extends overchamber 240 and along a portion of a side area of chamber 240. Moreparticularly, upper heel element 233 includes five downwardly-extendingprojections 235 and defines an opening 236 that interfaces with portionsof chamber 240, as described in greater detail below. Lower heel element234 is also shaped to conform with the contours of a lower area ofchamber 240 and extends under chamber 240 and along another portion ofthe side area of chamber 240. More particularly, lower heel element 234includes five upwardly-extending projections 237 that extend into spacesin chamber 240 and contact ends of projections 235. The lengths ofprojections 235 are partially dependent upon the lengths of projections237 and may vary. In some configurations of footwear 200, projections235 and 237 may be shorter or longer than the configuration depicted inthe figures. Together, however, projections 235 and 237 extendvertically along the side area of chamber 240. In other configurations,projections 235 and 237 may be absent such that substantially all of theside area of chamber 240 is exposed. The specific configurations of heelelements 233 and 234 will be more apparent with reference to FIGS. 38-40and the following discussion.

Heel elements 233 and 234 may be formed from a variety of materials,including both foamed and non-foamed polymer materials. In oneconfiguration, upper heel element 233 may be formed from a non-foamedpolymer material that distributes downward forces from the foot tochamber 240, and lower heel element 233 may be formed from a foamedpolymer material (e.g., polyurethane or ethylvinylacetate foam) thatprovides additional force attenuation. Examples of suitable non-foamedpolymer materials includes polyester, thermoset urethane, thermoplasticurethane, various nylon formulations, rubber, or blends of thesematerials. In addition, upper heel element 233 may be formed from a highflex modulus polyether block amide, such as PEBAX, which is manufacturedby the Atofina Company. Another suitable material for upper heel element233 is a polybutylene terephthalate, such as HYTREL, which ismanufactured by E.I. duPont de Nemours and Company. Composite materialsmay also be formed by incorporating glass fibers or carbon fibers, forexample, into the polymer materials discussed above in order to enhancethe strength of upper heel element 233.

In other configurations of sole structure 230, heel elements 233 and 234may both be formed from a foamed polymer material with either the sameor different densities. Midsole 231 may also be formed as a unitary(i.e., one piece) element that defines a void for receiving chamber 240.That is, rather than forming midsole 231 from three elements 232-234, asingle midsole element may be utilized instead, with chamber 240 beingat least partially encapsulated therein. Alternately, forward element232 and lower heel element 234 may be formed as a unitary element.Accordingly, the specific configuration and materials selected formidsole 231 may vary significantly.

Chamber 240 has a configuration of a fluid-filled bladder with a centralarea 241 surrounded by six lobes 242 a-242 f, as depicted in FIGS.41-45. Suitable materials for chamber 240 and the fluid within chamber240 include any of the materials and fluids discussed above for priorart chambers or chambers 40, 40′, and 40″. Lobes 242 a-242 f extendradially outward from central area 241 and respectively have distal ends243 a-243 f. Accordingly, lobes 242 a-242 f extend outward in differentdirections from a periphery of central area 241, and lobes 242 a-242 fdefine various spaces between each other. Central area 241 and lobes 242a-242 f are formed from a first surface 245, an opposite second surface246, and a sidewall 247 of chamber 240. Accordingly, surfaces 245 and246 extend over opposite sides of each of central area 241 and lobes 242a-242 f. First surface 245 has a generally concave configuration, asdepicted in the cross-sections of FIGS. 44A-44C, and defines anelliptical protrusion 244 a that extends outward from central area 241.Similarly, at least a periphery of second surface 246 has a generallyconcave configuration and defines an elliptical protrusion 244 b thatalso extends outward from central area 241. Whereas protrusion 244 aextends in an upward direction in footwear 200, protrusion 244 b extendsin a downward direction.

When chamber 240 is incorporated into footwear 200, protrusion 244 aextends upward from first surface 245 and into opening 236 of upper heelelement 233. That is, at least a portion of opening 236 has anelliptical shape that receives protrusion 244 a when chamber 240 isincorporated into footwear 200. The thickness of upper heel element 233and the height of protrusion 244 a may be selected such that an uppersurface of protrusion 244 a is flush with an upper surface of upper heelelement 233. A foot located within the void in upper 220 may besupported, therefore, by each of protrusion 244 a and upper heel element233. In some configurations, however, the upper surface of protrusion244 a may be above or below the upper surface of upper heel element 233.Although the foot may be supported by each of protrusion 244 a and upperheel element 233, an insole or material elements from upper 220 mayextend between the foot and midsole 231.

Distal ends 243 a-243 f extend to a sidewall of midsole 231 and areexposed at the sidewall when chamber 240 is incorporated into footwear200. Accordingly, distal ends 243 a-243 f are visible from an exteriorof footwear 200. In comparison with the dimensions of lobes 242 a-242 fadjacent to central area 241, distal ends 243 a-243 f generally havegreater height and width dimensions. That is, lobes 242 a-242 f flare orotherwise expand outward adjacent to distal ends 243 a-243 f. Whenexposed at the sidewall of midsole 231, the greater dimensions increasethe apparent size of chamber 240. That is, the relatively large size ofdistal ends 243 a-243 f provides an impression that chamber 240 hasrelatively large overall dimensions when incorporated into footwear 200.

Projections 235 and 237 extend into the spaces formed between lobes 242a-242 f when chamber 240 is incorporated into footwear 200. Moreparticularly, projections 235 extend downward from upper heel element233 and into an upper portion of the spaces, and projections 237 extendupward from lower heel element 234 and into a lower portion of thespaces. End portions of projections 235 and 237 contact each other inthe spaces and may be joined to each other. As depicted, projections 237of lower heel element 234 extend further into the spaces thanprojections 235 of upper heel element 233. In a configuration whereinupper heel element 233 is formed from a non-foamed polymer material andlower heel element 234 is formed from a foamed polymer material, thisconfiguration effectively forms foam columns that extend into the spacesbetween lobes 242 a-242 f. That is, forming lower heel element 234 froma foamed polymer material positions columns of a foam material withinthe spaces. Whereas a center of the foot is primarily supported bychamber 240, a periphery is at least partially supported by the polymerfoam material (i.e., projections 237) of lower heel element 234.

The size and locations of projections 237 are determined by theconfigurations of lobes 242 a-242 f and the spaces between lobes 242a-242 f. As discussed above, lobes 242 a-242 f flare outward adjacent todistal ends 243 a-243 f. In this configuration, a majority of the spacesbetween lobes 242 a-242 f are shifted inward from the periphery ofchamber 240. A majority of the foam columns formed by projections 237are also, therefore, shifted inward from the periphery of chamber 240.As a comparison, the spaces between lobes 42 a′-42 g′ of chamber 40′flare outward, thereby placing a majority of the polymer foam materialof midsole 31′ adjacent to the periphery of midsole 31′.

Chamber 240 and its arrangement with midsole 231 produces a relativelylarge deflection for a given load during initial stages of compressionwhen compared to the fluid-filled chambers discussed in the Backgroundof the Invention section above. As the compression of chamber 240increases, however, the stiffness of chamber 240 increases in acorresponding manner due to the structure of chamber 240 and the mannerin which chamber 240 is incorporated into midsole 231. As with chambers40 and 40′ above, three phenomena operate simultaneously to produce thiseffect: (a) pressure ramping, (b) the properties of the foam material inmidsole 231, and (c) film tensioning. Each of these phenomena will bedescribed in greater detail below.

Pressure ramping is the increase in pressure within chamber 240 thatoccurs as a result of compressing chamber 240. In effect, chamber 240has an initial pressure and initial volume when not being compressedwithin midsole 231. As midsole 231 is compressed, however, the effectivevolume of chamber 240 decreases, thereby increasing the pressure of thefluid within chamber 240. The increase in pressure operates to provide aportion of the cushioning response of midsole 231. That is, as thepressure increases, the stiffness of sole structure 230 increases in acorresponding manner. The volume of the fluid within chamber 240 has aneffect upon pressure ramping. In general, the pressure within chamber240 will increase more quickly for a given compressive force whenchamber 240 has a lesser fluid volume, and the pressure within chamber240 will increase more slowly for a similar compressive force whenchamber 240 has a greater fluid volume. Both first surface 245 andsecond surface 246 have a concave configuration that effectivelydecreases the fluid volume of chamber 240. Accordingly, the pressure ofchamber 240 will increase more quickly when a compressive force isapplied than in a similar chamber that does not have concave surfaces.The degree of concavity in surfaces 245 and 246 may be used, therefore,to modify the degree of pressure increase for a given compressive force.

The properties of the foam material also affect the cushioning responseof midsole 231. With regard to the configuration discussed above, thefoam material in midsole 231 is concentrated at an area that is spacedinward from distal ends 243 a-243 f. A change in the number of lobes 242a-242 f may be utilized, for example, to decrease the ratio of air tofoam in peripheral portions of midsole 231. A change in the locationsand dimensions of the spaces between lobes 242 a-242 f may also beutilized to affect the ratio of air to foam in peripheral portions ofmidsole 231. These changes in midsole 231 may be utilized to increasethe overall stiffness of midsole 231 during compression. Accordingly,the geometry of the foam material and the corresponding geometry ofchamber 240 have an effect upon the cushioning response.

Finally, the concept of film tensioning has an effect upon thecushioning response. This effect is best understood when compared topressurized prior art chambers. In the prior art chambers, the pressurewithin the chambers places the outer layers in tension. As the prior artchambers are compressed, however, the tension in the outer layers isrelieved or lessened. Accordingly, compression of the prior art chambersoperates to lessen the tension in the outer layers. In contrast with thepressurized prior art chambers, the tension in first surface 245, whichis generally concave, increases in response to compression due tofurther bending or stretching of first surface 245. This increase intension contributes to the cushioning response discussed above.

Pressure ramping, the properties of the foam material, and filmtensioning operate together to provide the cushioning response of solestructure 230. The specific effect that pressure ramping, the propertiesof the foam material, and film tensioning have upon the cushioningresponse varies based upon location with respect to chamber 240. Atperimeter portions of chamber 240, which corresponds with the locationsof distal ends 243 a-243 f, the properties of chamber 240 are largelyresponsible for determining the degree of stiffness in midsole 231. Inareas corresponding with the spaces between lobes 242 a-242 f (i.e., anarea spaced inward from the perimeter portions of chamber 240), theproperties of the foam material of lower heel element 234 providesreduced compliance and, therefore, increases the correspondingstiffness. That is, the properties of chamber 240 and the foam materialof lower heel element 234 cooperatively operate to determine the degreeof stiffness in portions of midsole 231. As the location tends towardcentral area 241, the ratio of chamber 240 to the foam materialincreases to allow a relatively large deflection, and the dominantphenomena that attenuate forces and absorb energy are film tensioningand pressure ramping.

Based upon the considerations of pressure ramping, the properties of thefoam material, and film tensioning, the stiffness of midsole 231 ismodifiable to provide a desired degree of force attenuation. Forexample, the volume of chamber 240, the number and shape of lobes 242a-242 f, the slope of sidewall 247, the thickness of surfaces 245 and246, the material utilized to form the exterior of chamber 240, and theposition and orientation of chamber 240 within midsole 231 may be variedto modify the cushioning response. In addition, the properties of thefoam material, including the hardness and thickness, may also beadjusted to modify the cushioning response. By varying these and otherparameters, therefore, midsole 231 may be custom tailored to a specificindividual or to provide a specific cushioning response duringcompression.

Pressure ramping, the properties of the foam material, and filmtensioning provide examples of characteristics that affect thecushioning response of midsole 231. Other factors may also have aneffect upon the cushioning response. For example, the slope of sidewall247 has an effect upon the stiffness of chamber 240. Whereas distal ends243 a-243 f have a more vertical orientation, the portions of sidewall247 within the spaces between lobes 242 a-242 f slope between firstsurface 245 and second surface 246. When compressed, the sloping surfacecollapses smoothly, whereas more vertical surfaces buckle and impartgreater resistance to compression. Accordingly, the configuration ofsidewall 247 ensures that interior portions of chamber 247 collapse moresmoothly than peripheral portions.

As the size of footwear 200 increases, the overall size of chamber 240and the mass of the individual wearing footwear 200 also increases. If,however, all dimensions of chamber 240 increase proportionally, thecushioning response of midsole 231 will vary to provide less stiffnessfor larger versions of footwear 200 and more stiffness for smallerversions of footwear 200. That is, merely proportionally changing thedimensions of chamber 240 does not provide a comparable cushioningresponse for footwear 200 as the size of footwear 200 changes. In orderto provide a comparable cushioning response for footwear 200 as the sizeof footwear 200 changes, various dimensions of chamber 240 change atdifferent rates as the overall dimensions of chamber 240 change, asdiscussed below.

With reference to FIG. 46, three chambers 240 a-240 c are depicted.Chamber 240 a is dimensioned for a version of footwear 200 suitable fora men's size 12.5, chamber 240 b is dimensioned for a version offootwear 200 suitable for a men's size 9.5, and chamber 240 c isdimensioned for a version of footwear 200 suitable for a men's size 6.5.Each of chambers 240 a-240 c are depicted as having the following: (a) adimension 251 that represents a length of protrusion 244 a, (b) adimension 252 that represents a width of protrusion 244 a, (c) variousdimensions 253 that represent a distance between protrusion 244 a andthe spaces between lobes 242 a-242 f, (d) various dimensions 254 thatrepresent a maximum depth of the spaces between lobes 242 a-242 f, (e)various dimensions 255 that represent a maximum width of the spacesbetween lobes 242 a-242 f, and (f) a dimension 256 that represents adistance between lobes 242 c and 242 d.

In comparing dimensions 251 of chambers 240 a-240 c, the length ofprotrusion 244 a changes in proportion to the change in overall lengthof chambers 240 a-240 c. That is, dimension 251 changes in directproportion to the change in overall length of chambers 240 a-240 c. If,for example, a difference in overall length between chambers 240 c and240 b is 30 percent, then the difference in dimensions 251 for chambers240 c and 240 b would also be 30 percent. Similarly, if a difference inoverall length between chambers 240 b and 240 a is 30 percent, then thedifference in dimensions 251 for chambers 240 b and 240 a would also be30 percent.

Whereas lengths of protrusions 244 a (i.e., dimensions 251) change inproportion to the change in overall length, the widths of protrusions244 a (i.e., dimensions 252) change at one-third the proportional changein overall width. If, for example, a difference in overall width betweenchambers 240 c and 240 b is 30 percent, then the difference indimensions 252 for chambers 240 c and 240 b would be 10 percent (i.e.,one-third of 30 percent). Similarly, if a difference in overall widthbetween chambers 240 b and 240 a is 30 percent, then the difference indimensions 252 for chambers 240 b and 240 a would also be 10 percent.Accordingly, protrusion 244 a of chamber 240 a is more eccentric (i.e.,elongate) than protrusions 244 a of chambers 240 b and 240 c.

Whereas dimensions 251 and 252 change between chambers 240 a-240 c,dimension 253 remains substantially constant. That is, the distancesbetween protrusions 244 a and the spaces between lobes 242 a-242 f aresubstantially the same for each of chambers 240 a-240 c. Accordingly, ifdimension 253 is one centimeter for chamber 240 a, then dimension 253 isalso one centimeter for each of chambers 240 b and 240 c. By holdingdimension 253 constant and only changing dimensions 252 by one-third theproportional change in overall width, the maximum depth of the spacesbetween lobes 242 a-242 f (i.e., dimension 254) increases as the size ofchamber 240 increases. Accordingly, dimension 254 is larger for chamber240 b when compared to chamber 240 c, and also larger for chamber 240 awhen compared to chamber 240 b.

The change in the maximum width of the spaces between lobes 242 a-242 f(i.e., dimension 255) partially depends upon the size of footwear 200that chamber 240 is intended to be used with. For sizes less than size9.5 (i.e., smaller than chamber 240 b), dimension 255 changes inproportion to the overall change in length and width of chamber 240. If,for example, a difference in size between chambers 240 c and 240 b is 30percent, then the difference in dimensions 255 for chambers 240 c and240 b would also be 30 percent. In contrast, for sizes greater than size9.5 (i.e., larger than chamber 240 b), dimension 255 changes at twicethe rate of overall change in length and width of chamber 240. If, forexample, a difference in size between chambers 240 b and 240 a is 30percent, then the difference in dimensions 255 for chambers 240 b and240 a would be 60 percent. Accordingly, the degree of change indimension 255 primarily depends upon the size of chamber 240.

The distance between most of lobes 242 a-242 f change in proportion tothe overall change in the size of chamber 240. The change in thedistance between lobes 242 c and 242 d (i.e., dimension 256), however,also partially depends upon the size of footwear 200 that chamber 240 isintended to be used with. For sizes less than size 9.5 (i.e., smallerthan chamber 240 b), dimension 256 changes in proportion to the overallchange in length and width of chamber 240. If, for example, a differencein size between chambers 240 c and 240 b is 30 percent, then thedifference in dimensions 256 for chambers 240 c and 240 b would also be30 percent. In contrast, for sizes greater than size 9.5 (i.e., largerthan chamber 240 b), dimension 256 changes at four times the rate ofoverall change in length and width of chamber 240. If, for example, adifference in size between chambers 240 b and 240 a is 30 percent, thenthe difference in dimensions 256 for chambers 240 b and 240 a would be120 percent. Accordingly, the change in dimension 256 also depends uponthe size of chamber 240.

Based upon the above discussion, different sizes of footwear 200incorporate chambers 240 with different proportions. Although manyfeatures of chamber 240 (e.g., lobes, spaces, protrusions, concavesurfaces, sloped sidewall) are present in chambers 240 for differentsizes of footwear 200, the proportions of various features of chambers240 may vary. This system by which dimensions 251-256 change as the sizeof chamber 240 changes has the effect of providing a comparablecushioning response for different sizes of footwear 200. Accordingly,individuals wearing footwear 200 may experience a comparable cushioningresponse, regardless of the size of footwear 200.

Chamber 240 may be formed using a mold that is structurally similar tomold 100, which is discussed above in relation to chamber 40′. The moldthat is utilized to form chamber 240 may, therefore, include a bendingzone and a forming zone that have different functions. The bending zoneis responsible for bending a parison prior to bonding. The forming zoneincludes a central area, lobe areas, and sidewall areas thatrespectively form central area 241, lobes 242 a-242 f, and distal ends243 a-243 f. The forming zone is responsible, therefore, for impartingthe actual shape of chamber 240 to the parison. An advantage of bendingsides of the parison relates to a position of a parting line 248 inchamber 240, as depicted in FIG. 47. Parting line 248 corresponds withthe area where the opposite mold portions meet adjacent to bladder 240.With reference to FIG. 47, parting line 248 does not merely extendvertically across sidewall 247. Instead, parting line 248 follows anon-linear course having a wave-like pattern that extends around distalends 243 a-243 f. More specifically, parting line 248 extendshorizontally between sidewall 247 and first surface 245 at upper ends ofdistal ends 243 a-243 f. Parting line 248 then extends vertically acrosssidewall 247 along the sides of distal ends 243 a-243 f. Accordingly, atleast a portion of parting line 247 extends between first surface 245and second surface 246. Parting line 248 also extends horizontallybetween sidewall 247 and second surface 246 in areas between lobes 242a-242 f. When incorporated into an article of footwear, as depicted inFIGS. 35 and 36, parting line 248 will generally not be visible or willat least be in a portion of chamber 240 that does not significantlyobstruct visibility through distal ends 243 a-243 f. That is, partingline 248 may be positioned so to extend adjacent to distal ends 243a-243 f. Parting line 248 is, therefore, not centered in sidewall 247.

In forming chamber 240 with a blow molding process, air may be utilizedto induce sides of the parison to contact surfaces of the mold. In orderto seal chamber 240, a pillow blowing process may be utilized, wherein atube that is used to introduce air during the blow molding process issealed to trap the air within chamber 240. Accordingly, chamber 240 maybe sealed by closing the tube that introduces air in the blow moldingprocess, and no separate inflation tube or inflation process isnecessary.

CONCLUSION

The configuration of sole structure 230 discussed above provides anexample of the various configurations that components of sole structure230, including elements 232-234 and chamber 240 may exhibit. Referringto FIG. 48, a top plan view of an alternate configuration of solestructure 230 is depicted. In comparison with the configuration of FIG.38, upper heel element 233 forms an entirely elliptical opening 236.That is, opening 236 forms a closed aperture that extends through upperheel element 233. In order to control the degree of pronation thatoccurs during running, chamber 240 may be tapered between medial side215 and lateral side 214, as depicted in FIGS. 49A and 49B. That is,medial side 215 may exhibit greater thickness than lateral side 214. Asanother variation, second surface 246 may have a planar or otherwisenon-concave configuration, as depicted in FIG. 49C. The degree to whichprojections 237 extend upward may also vary. For example, projections237 may only extend partially between surfaces 245 and 246, as depictedin FIGS. 50A and 50B. The shape of protrusion 244 a may also vary tohave an octagonal or diamond shaped configuration, as depicted in FIGS.51A and 51B, or protrusion 244 a may have a variety of other shapes,including round, triangular, rectangular, pentagonal, or a non-regularshape, for example. In some configurations, protrusion 244 a may also beabsent, as in FIG. 51C. Additionally, the number of lobes 242 a-242 fmay vary, as depicted in FIG. 51D, wherein chamber 240 has four lobes242 a-242 d. Accordingly, the configuration of sole structure 230 andvarious components thereof may vary significantly within the scope ofthe invention.

The present invention is disclosed above and in the accompanyingdrawings with reference to a variety of embodiments. The purpose servedby the disclosure, however, is to provide an example of the variousfeatures and concepts related to the invention, not to limit the scopeof the invention. One skilled in the relevant art will recognize thatnumerous variations and modifications may be made to the embodimentsdescribed above without departing from the scope of the presentinvention, as defined by the appended claims.

1. A fluid-filled chamber for an article of footwear, the chamber comprising a central area and a plurality of lobes extending outward from the central area, the central area and the lobes defining a first concave surface and an opposite second concave surface of the chamber.
 2. The fluid-filled chamber recited in claim 1, wherein the first concave surface defines a first protrusion extending outward from the central area, and the second concave surface defines a second protrusion extending outward from the central area, the first protrusion being positioned opposite the second protrusion.
 3. The fluid-filled bladder recited in claim 2, wherein at least one of the first protrusion and the second protrusion are elliptical.
 4. The fluid-filled chamber recited in claim 1, wherein the lobes define a space between two of the lobes located adjacent to each other, and a distance across the space and between the lobes located adjacent to each other is greater proximal the central area than at distal ends of the lobes.
 5. The fluid-filled chamber recited in claim 1, wherein the lobes define a space between two of the lobes located adjacent to each other, and a sidewall of the chamber slopes between the first concave surface and the second concave surface in the space.
 6. The fluid-filled chamber recited in claim 1, wherein the chamber is devoid of internal connections that join the first concave surface with the second concave surface, and a fluid pressure within the chamber is in a range of zero and five pounds per square inch.
 7. A fluid-filled chamber for an article of footwear, the chamber comprising a central area and a plurality of lobes extending outward from the central area, the lobes including a first lobe and a second lobe that are adjacent to each other and define a space extending between the first lobe and the second lobe, a distance across the space and between the first lobe and the second lobe being greater proximal the central area than at distal ends of the first lobe and the second lobe.
 8. The fluid-filled chamber recited in claim 7, wherein at least one of the first lobe and the second lobe flares outward at the distal ends.
 9. The fluid-filled chamber recited in claim 7, wherein the chamber is devoid of internal connections that join opposite surfaces of the chamber.
 10. The fluid-filled chamber recited in claim 7, wherein a fluid pressure within the chamber is in a range of zero and five pounds per square inch.
 11. The fluid-filled chamber recited in claim 7, wherein the central area and the lobes define a first surface and an opposite second surface of the chamber, each of the first surface and the second surface having a concave configuration.
 12. The fluid-filled chamber recited in claim 7, wherein the central area and the lobes define a first surface and an opposite second surface of the chamber, the first surface having a concave configuration, and the first surface defining a protrusion extending outward from the central area.
 13. A fluid-filled chamber for an article of footwear, the chamber comprising a first surface, a second surface, and a sidewall extending between the first surface and the second surface, the chamber defining a plurality of indentations extending inward from the sidewall, a width of at least one of the indentations being less at the sidewall than in an area that is spaced inward from the sidewall.
 14. The fluid-filled chamber recited in claim 13, wherein the first surface is concave.
 15. The fluid-filled chamber recited in claim 14, wherein the first surface defines a protrusion extending outward from a central area of the chamber.
 16. The fluid-filled chamber recited in claim 15, wherein the protrusion is elliptical.
 17. The fluid-filled chamber recited in claim 14, wherein the second surface is concave.
 18. The fluid-filled chamber recited in claim 13, wherein the sidewall slopes between the first surface and the second surface in the indentation.
 19. The fluid-filled chamber recited in claim 13, wherein the chamber is devoid of internal connections that join the first surface with the second surface.
 20. The fluid-filled chamber recited in claim 13, wherein a fluid pressure within the chamber is in a range of zero and five pounds per square inch. 